Determining wait-state
Determining wait-state
(OP)
Hi everyone,
How do I determine the wait-state of the external flash memory to a processor (ADI blackfin). What characteristic of the CPU or external flash determine the wait-state? Thank you very much in advance!
James
How do I determine the wait-state of the external flash memory to a processor (ADI blackfin). What characteristic of the CPU or external flash determine the wait-state? Thank you very much in advance!
James





RE: Determining wait-state
RE: Determining wait-state
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Determining wait-state
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Determining wait-state
Are these numbers enough to determine the wait-state? If yes, how do I calculate it?
The processor core runs at 400 MHz
External bus interface runs at 80 MHz
SDR SDRAM's "cycle time" = 7.5ns
Best regards,
James
RE: Determining wait-state
Didn't you state that backwards? If the processor is faster than the memory then the processor will have to (insert) wait (states) until the memory is ready.
JN,
Pull up a datasheet for your memory. You'll see a timing diagram that will show you what parameters to watch for. You'll also see the same type of parameters in the processor datasheet (like Figure 11 and Figure 12 in the ADSP-BF534 datasheet). You need to make sure the processor isn't too fast for the memory; otherwise you'll need to add wait states.
John D
RE: Determining wait-state
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Determining wait-state
IRstuff:
Define "school". I am here to learn. If that's what what you call schooling, then yes, I am attending Eng-Tips school. I hope you understand that something which is obvious to you may not be obvious to other people. Just imagine what would happen if every question on this site is answered by "Is this for school?"
To answer your REAL question. No, this is for work.
Anyway, thank you.
James
RE: Determining wait-state
Yeah, reverse that :(
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Determining wait-state
SDRAM interfaces have at least a dozen variables...
ht
By the time you're able to formulate a valid question, you could answer it yourself.
I started looking at RAM specs in order to upgrade an old PC. I learned a lot, but lost interest and bought a new PC. LOL.
RE: Determining wait-state
If you are interested or think this may be an issue for you, Howard Johnson has a really good write up of this in his book High Speed Digital Design.